Conventionally, as means for supplying stabilized electric power with low thermal loss and in addition with comparatively high efficiency in cases where input-output differences are large, there have been widely used switching regulators (chopper regulators) that generate a constant output voltage from an input voltage by the turning on and off of an output transistor (i.e., through control of the duty ratio thereof).
Such a switching regulator generally includes a short-circuit current protection circuit that limits its output current in the event of an overload or output short-circuit (for example, see patent document 1).
As another conventional technology related to the present invention, there has been disclosed and proposed a power semiconductor device including an overcurrent preventing circuit that detects whether an output transistor operates within a safe operation range to prevent the output transistor from falling outside the permissible loss range and being destroyed by heat (see patent document 2).
Patent document 1: JP-A-2002-300773
Patent document 2: JP-A-2003-078362